autotest: Add test support for 802.11ac

Update hostapd_config to support 802.11ac, and add a SimpleConnect test
for it as well. For routers without 802.11ac support, TEST_NA will be
raised.

Test is performed using Panther router with WP2, which only supports
channel width of 80MHz.

The support for 802.11ac AP for Panther requires test-ap-group build #10
or newer.

BUG=chromium:419930
TEST=Run network_WiFi_SimpleConnect.wifi_check5VHT80

Change-Id: I3fd6bc834a18d0b33af79061a8a3c2f35d0f88ec
Reviewed-on: https://chromium-review.googlesource.com/224118
Reviewed-by: Peter Qiu <[email protected]>
Tested-by: Peter Qiu <[email protected]>
Reviewed-by: Paul Stewart <[email protected]>
Commit-Queue: Peter Qiu <[email protected]>
diff --git a/server/site_linux_system.py b/server/site_linux_system.py
index 3739a55..4e519fe 100644
--- a/server/site_linux_system.py
+++ b/server/site_linux_system.py
@@ -33,6 +33,7 @@
     CAPABILITY_IBSS = 'ibss_supported'
     CAPABILITY_SEND_MANAGEMENT_FRAME = 'send_management_frame'
     CAPABILITY_TDLS = 'tdls'
+    CAPABILITY_VHT = 'vht'
 
 
     @property
@@ -178,6 +179,8 @@
         for phy in self.phy_list:
             if 'tdls_mgmt' in phy.commands or 'tdls_oper' in phy.commands:
                 caps.add(self.CAPABILITY_TDLS)
+            if phy.support_vht:
+                caps.add(self.CAPABILITY_VHT)
         return caps